18 Apr
2007
18 Apr
'07
4:46 p.m.
Ethan Dicks [ethan.dicks at gmail.com] wrote:
[W]H-27 problems...
I can get the system to read in the boot sector from the floppy,
but it hangs about the time RT-11 is running far enough to
turn the interrupts on.
Dumb question - you _do_ have the RX-01/Extended switch set to RX-01,
right? Extended mode isn't DEC compatible and the RT11 driver won't work
with it.
Bob
18 Apr
18 Apr
7:51 p.m.
On 4/18/07, Robert Armstrong <bob at jfcl.com> wrote:
It is a dumb questions - my dumb answer is I certainly hope I did. I
will check the state of the switch the next time I am in front of the
box and if it's wrong, slap myself and start debugging from the top.
Ethan Dicks
[ethan.dicks at gmail.com] wrote:
[W]H-27 problems...
I can get the system to read in the boot sector from the floppy,
but it hangs about the time RT-11 is running far enough to
turn the interrupts on.
Dumb question - you _do_ have the RX-01/Extended switch set to RX-01,
right? Extended mode isn't DEC compatible and the RT11
driver won't work
with it.
I had a vague idea that I didn't want the switch in the extended
(Heath) position, but I didn't know the specific consequences. I have
a hint of a dim memory that perhaps one could format blank media in
extended mode, but I wasn't trying to format, just to boot existing
RT-11 v4 floppies that work fine in a MINC-11.
-ethan
19 Apr
19 Apr
2:07 p.m.
New subject: WH-27 Problems (was RE: Heathkit H8's, H9's and H-11's)
Ethan Dicks (ethan.dicks at gmail.com) wrote:
I had a vague idea that I didn't want the switch
in the extended
(Heath) position, but I didn't know the specific
consequences.
The [W]H-27 drives were both the best and the most disappointing part of
the H-11 system. BTW, the H-27 was the Heathkit build-it-yourself drive,
and the WH-27 was the ZDS already assembled version. AFAIK they were
otherwise identical.
There's a toggle switch on the front of the drive for "Extended" or
"RX-01" mode. RX-01 mode is completely DEC compatible, and will run RT-11
just fine, but note that "RX-01" really means RX01 - not RX02. Yes, the
[W]H-27 can read/write 512K diskettes, but not in DEC compatible mode.
Bummer!
In extended mode the drive could handle 512K diskettes, and it was capable
of other miracles such as the ability to format a completely blank diskette.
Yes, most people would not be impressed by a drive that can format
diskettes, but real DEC RX01/2 users never knew this joy.
So the bottom line is that if you want to run standard RT-11 on the H-11,
you have to set the switch to RX-01 mode and you have the equivalent of an
RX01 drive. No double density, and no formatting.
Now, HT-11 worked in extended mode and HT-11 also had a program that could
format diskettes. Since HT-11 was basically RT-11, one would think that you
could just install the WH-27 device driver and format program on a RT-11
system and have something that worked in extended mode, but I've never tried
that.
Actually, I don't know what's become of the Heath specific software for
the H-11, such as the WH-27 driver and the format program. Maybe somebody
has an archive somewhere?
Bob
2:31 p.m.
New subject: WH-27 Problems (was RE: Heathkit H8's, H9's and H-11's)
On 4/19/07, Robert Armstrong <bob at jfcl.com> wrote:
The [W]H-27 drives were both the best and the most
disappointing part of
the H-11 system...
Yes, most people would not be impressed by a drive
that can format
diskettes, but real DEC RX01/2 users never knew this joy.
And, except for Rainbow uses, most RX50 users never knew this joy, either.
At least the RX01 format was standard, and one could use a CP/M
machine or something else to drop the IBM 3740-compatible low-level
format on a blank disc. In practice, though, I just remember folks
buying pre-formatted media. Fortunately, I still have a couple of NOS
boxes, presuming they haven't self-destructed on the (dry) shelf. I
got them from a friend who used to run a computer media store (paper,
ribbons, diskettes, etc.). He had hundreds of pounds of 8" diskettes
of various flavors. He didn't know what to do with the ones marked
"DEC compatible", so he gave them to me when sales were disappointing.
Unfortunately, he pitched the whole lot out over ten years ago
because he was tired of looking at them. I was out of the country, or
perhaps he would have asked me to come by and collect them.
So the bottom line is that if you want to run
standard RT-11 on the H-11,
you have to set the switch to RX-01 mode and you have the equivalent of an
RX01 drive. No double density, and no formatting.
Right... I know I was using real RX01 media, RT-11 v4.0, so I know I
wasn't getting tripped up by RX02 issues.
Now, HT-11 worked in extended mode and HT-11 also
had a program that could
format diskettes. Since HT-11 was basically RT-11, one would think that you
could just install the WH-27 device driver and format program on a RT-11
system and have something that worked in extended mode, but I've never tried
that.
Perhaps, but, then again, with a "custom" OS, there might have been
some check somewhere in the Monitor to enforce compliance. It will be
interesting to take apart the OS and see where the differences lie.
One could then, presumably, build a patch kit to "transform" a genuine
RT-11 kit into HT-11, as folks already do with various versions of
Infocom adventures (i.e. - *you* get a legitimate copy of the game
file, then acquire and apply patches to it to turn it into the
different release versions of the game. Since the patches are based
on a known quantity and aren't themselves the game, they are made
freely available)
Actually, I don't know what's become of the
Heath specific software for
the H-11, such as the WH-27 driver and the format program. Maybe somebody
has an archive somewhere?
I have never seen one, but another list member has offered to send me
some H-11 media. Once I get things working, I'll see about archiving
it.
Thanks for all the great info, Bob.
-ethan
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